Percentage Water Content in Popcorn Kernels

Core Skills: Error Lab

Abstract

The purpose of this experiment was to calculate and compare the percentage weight loss of popcorn kernels from two different brands. This was achieved by measuring the mass of 10 kernels from each of the popcorn brands before and after popping.

Measuring the weight difference made it possible to know how much water was present in the kernel. The measurements showed that the unpopped ‘Brand B’ kernel had a higher initial and final mass than the ‘Brand A’ kernel. However, it had a lower percentage of weight loss (9.58% and

15.69% respectively) which meant it was comprised of less water. Brand A kernels had the optimum water composition; whilst the Brand B kernels were over-dried at a 9.58% water composition is significantly lower than the optimum 14-15%. As a result of the higher moisture content Brand A was more visually stimulating than its counterpart.

Introduction

The objective of this investigation was to measure the average percent of water, contained in the kernels of the 2 different popcorn brands that were chosen.

Popping corn, commonly referred to as ‘popcorn’ is a unique type of corn that pops and expands when heated. 1 Popcorn is primarily made up of starch but it also has some water, fat and proteins. It has a hard resistant external layer called a hull-under the hull there exists a dense opaque starch layer-it also has an innermost layer which is also a starch that has irregular polygons and clear grains. What makes popcorn an extraordinary corn is the high proportions of the clear starch in its inner layer. These proportions are what make it possible for popcorn to expand 20-40 times of its original volume.2 It has been proposed that popcorn should contain 13-15% percent of water in order to attain maximum expansion. 3

As the kernel is heated the water inside it turns into steam and expands increasing the pressure. Popping happens at temperatures of 450K, which is equivalent to a pressure of 135 psi inside the kernel, the hull cannot withstand this pressure. Most of the water in the kernel is superheated at the moment of popping which provides the driving force required for the expansion of the kernel once the external hull bursts.4

Experiment

Equipment Required:

• Popcorn kernels

• Bunsen burner

• safety glasses

• flask (glass)

• heat-resistant gloves

• clamp

Procedure:

1. Pick out 10 kernels from each brand of popcorn

1. Weigh each kernel of popcorn and record the measurements

1. Securely attach the clamp onto the flask

1. Pop the kernels one at a time by placing it in a flask and heating the flask gently over the Bunsen burner. (Use the clamp to hold the flask over the Bunsen burner). Ensure that safety goggles and heat-resistant gloves are worn.

1. As soon as the kernel pops, proceed to remove it from the flask. (Do this as quickly as possible to prevent the popcorn from burning)

1. Weigh the popped popcorn and record the measurements

Potential Hazards:

• Take the necessary precautions when heating the popcorn with the Bunsen burner to prevent any burns

• Do not eat the popcorn, as a laboratory is not a safe environment to ingest food

Results

Brand A

[pic 1]

Figure (I) a table showing the initial weight of Brand A kernels. Along with its mean, standard deviation and coefficient of variation

[pic 2]

Figure (II) is a table showing the final weight of Brand A kernels. Along with the mean, standard deviation and coefficient of variation

[pic 3]

Figure (III) is a table showing the weight change of Brand A kernels. Along with the mean, standard deviation and coefficient of variation

Brand B

[pic 4]

Figure (IV) is a table showing the initial weight of Brand B kernels. Along with the mean, standard deviation and coefficient of variation

[pic 5]

Figure (V) is a table showing the final weight of Brand B kernels. Along with the mean, standard deviation and coefficient of variation

[pic 6]

Figure (VI) is a table showing the weight change of Brand B kernels. Along with the mean, standard deviation and coefficient of variation

[pic 7]

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35

30

25

[pic 12]Brand A  [pic 13]Brand B

20

15

10

5

Figure (VII) is a scatter graph showing the average weight change of both brands of popcorn plotted against the number of observations

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